This invention relates generally to the conveyance of granular material and, in particular, to an improved vehicle for unloading harvested feed grains which includes both a horizontal and a vertical auger to unload grain from the vehicle bin or tank. A pressure-relief box is mounted to the horizontal auger to assist during the start of material unloading by relieving built-up pressure in the auger at a point adjacent its mating with the second vertical auger portion.
Screw conveyers, in general, have been conventionally used for many years to transfer grain or other granular or comminuted materials. In this regard, numerous improvements and variations have been made to these screw conveyors over the years to accomplish special purposes or to eliminate problems experienced with existing conveyor usage.
For example, special concern has been directed to the need for conveying granular material over substantial horizontal distances using a single screw conveyor channel or tube. In Metsa-Ketela, U.S. Pat. No. 4,059,508, this problem was addressed with the solution being to provide a plurality of bypass means 18 to permit continued transport of the granular material passed the several transverse wall means 36 and bearing means 16 needed to support the several conveyors and thereby to convey the material over long distances.
In Rasmussen, U.S. Pat. No. 3,232,419, the problem addressed was the transport of finely divided particles from a region at one pressure to a region at a different pressure without either the loss of pressure from the region of super-atmospheric pressure or the addition of air into the region of sub-atmospheric pressure. The solution disclosed in Rasmussen was to provide a second screw impellor resisting the movement of material through the casing and causing the material to thereby back up and form a pile extending upward into a enlarged chamber disposed above the casing at that point. The material then forms an inclined surface down toward the nearby outlet opening. The material sliding down this surface exits through this outlet while the pile of material forms a seal preventing the exchange of pressure between the beginning and ending regions.
This specialization has also reached the farming industry. For example, self-unloading feed wagons similar to that disclosed in Hall, U.S. Pat. No. 2,439,541, have been around for many years. They generally include a wheel chassis with a hollow body mounted thereon, this body being substantially V-shaped in cross section and forming a container or bin for carrying the harvested grain. A first elongated screw conveyor is positioned near the bottom of this body for moving the grain through a discharge opening in one end thereof. A second screw conveyor is then affixed generally normal to and in registry with this first conveyor outside the body to further move the grain therethrough for discharge into a silo, grain truck or other storage container. A prime mover or other power source is provided to operably drive these interconnecting conveyor portions.
Hansen, U.S. Pat. No. 2,676,721, discloses one modification of this feed wagon designed to eliminate clogging of the grain in the wagon bin. A plurality of feeding and agitating augers are positioned at differing levels in the body with a drag, or belt, conveyor 27 positioned near the bottom to move the grain through the discharge opening. An impellor or blade 48 is rotatably positioned outside this discharge opening to drive the material downwardly into the first of a two-stage auger attachment for transporting the material into a different storage container.
Hansen, U.S. Pat. No. 2,839,208, discloses a further modification in which the impellor unit 42 acts to continuously throw the material from the feeding auger 24 into the vertical discharge auger portion 66.
Another variation of this basic feed wagon design is disclosed in Boone, U.S. Pat. No. 3,721,333, in which a power-operated swingable auger conveyor is disclosed for attachment to any suitable combine harvestor in order both to provide for multi-directional unloading of the grain and to facilitate efficient storage of the equipment.
Still a further problem not satisfactorily addressed by the prior art is the periodic build up of internal pressure in the conveyor sections, and the jamming and overloading it often produces. During the start of material conveyance, the grain is first conveyed horizontally, or at a slight incline, through the discharge opening in the bin and on to the point where transfer is made to the second mating auger portion. As previously stated, this second auger is generally affixed normal, i.e., at about a 90.degree. angle, to the first section and advances the grain in a substantially vertical direction to the final discharge spout or opening. Feed grains often clog and stick at this junction due at least in part to this acute angle between the two mating augers.
This condition is aggravated by the gravitational force that must be overcome in the transfer, and often results in a total binding and clogging of the horizontal conveyor, commonly referred to as "back charging." The condition is further aggravated by the fact that most feed grains must be harvested within a certain range of moisture content. For example, it is recommended that corn be harvested at a 27% to 30% moisture content. This increased moisture promotes sticking between the individual grains which leads to further jamming and clogging at the junction between the auger shafts. The condition is still further aggravated by the distance the horizontal feed auger must convey the grain outside the bin before mating with the vertical pickup auger. As this outside distance increases, so does the likelihood of clutching, wedging or jamming of the grain in the horizontal auger, particularly during the start of transfer therethrough.
The dangers of this jamming are great. For example, the majority of grain cart vehicles presently on the market are driven by power take-off means operably connected to the corresponding power take-off on the farm tractor used to pull the cart. It was early recognized that this increased drag in the screw conveyors could cause substantial wear and stress on the power transmission of the tractor, and could even seize or substantially damage the tractor if a total binding occurred.
For this reason, the majority of available farm equipment driven by power take-off means is equipped with either a shear pin or an adjustable slip clutch so the increased friction in the horizontal screw conveyor will overload this pin or clutch before damaging the tractor transmission. However, these devices merely lessen the damage and do not attempt to remedy the basic problem experienced with these conveyor arrangements.
Accordingly, the back charging of grain in vehicles equipped with these devices often results in shearing off the connecting pins or overloading and wearing the slip clutch, both of which require much downtime to remedy and thereby significantly lessen the efficiency of the harvesting operation.
With most grain unloading vehicles on the market, the problem of back charging is further confronted by mounting a baffle or shield in the grain bin directly above at least a portion of the exposed horizontal auger. This shield aids in controlling the rate of flow of grain into the auger itself and may substantially lessen the back charging problem in vehicles having little or no horizontal grain conveyance by the feed auger after it passes through the discharge opening in the bin. These shields are also often vertically adjustable to further aid in controlling grain flow.
The disadvantages of these shields, however, are several. First, their use restricts the possible designs for grain unloading vehicles as to the distance grain can be conveyed horizontally by the feed conveyor after it leaves the grain bin. In vehicles where this distance is any appreciable amount, such as more than two or three feet, the effectiveness of these shields in lessening the chances of jamming or back charging is substantially decreased, if not eliminated.
Second, the basic objective of these shields is to restrict the access and flow of grain into the auger channel inside the bin. When moisture content is high, or when clogging is noticed, the shields, if adjustable, are tightened down even more over the otherwise exposed screw conveyor to further restrict the access of grain. By so doing, the rate of flow or conveyance of grain through the augers is lowered and the time required to unload the vehicle is correspondingly increased. This condition is highly undesirable for most farmers, having only one or two unloading vehicles to keep up with their harvesting, or combining, operation. Time is of the essence in these circumstances. The loaded vehicle must be moved to the waiting truck or other storage location, unloaded, and then returned to the field for reloading from the combine with a minimum of elapsed time and energy. Otherwise, valuable harvesting time is lost and the efficiency of the farming operation is decreased.
For these reasons, shields and baffles of this type do not provide a total solution for the grain jamming and back charging problems identified above. As already indicated, ineffectiveness is particularly noticed in unloading vehicles or other farming equipment in which grain is conveyed any appreciable horizontal distance after leaving the grain bin and before transferring to the pickup auger.
The need for a total solution to, and not just a mitigation of, this overloading and back charging problem therefore has been and continues to be a major concern to the farming industry.